As is well known in electrosurgery, with a monopolar device configuration, electrical power is delivered from a power source to an active terminal provided with the device. The electrical energy from the device then is passed through the patient generally to a large surface, electrically dispersive ground pad, often referred to as the return terminal, located on the back or other suitable anatomical location of the patient, and then back to the power source. Conversely, bipolar devices include both the active and return electrodes on the device. Electrical current flows from the active electrode generally through localized tissue and then to the return electrode and back to the power source.
One often cited advantage of bipolar devices as compared to monopolar devices is the elimination of electrical current flowing through the patient to a ground pad. However, devices such as bipolar scissors tend to be fairly complex in attempting to electrically isolate the active electrical terminal (pole) from the other return electrical terminal (pole). Furthermore, as disclosed in U.S. Pat. No. 5,658,281 in the name of Heard entitled “Bipolar Electrosurgical Scissors and Method Of Manufacture”, one of the advantages of monopolar electrosurgical tools is that the surgeon can apply electrosurgical current whenever the conductive portion of the tool is in electrical contact with the patient. Thus, a surgeon may operate with monopolar electrosurgical tools from many different angles. In contrast, bipolar tools suffer from the drawback that the surgeon must carefully position the tool to ensure that both electrical poles are in electrical contact with the patient in order to apply electrosurgical current. This may limit the range of motion and the angle from which the surgeon can effectively use the bipolar tool.
However, with dry tip electrosurgical devices, both monopolar and bipolar, the temperature of tissue being treated may rise significantly higher than 100° C., possibly resulting in tissue desiccation, tissue sticking to the electrodes, tissue perforation, char formation and smoke generation.
One attempt with monopolar scissors, in order to restrict the electric current flow through the patient, has been to decrease the size of the active electrode to only a portion of the confronting (shearing) surfaces. In this manner, the chance that a surgeon may inadvertently conduct current into and burn surrounding tissue is also reduced. One such solution, as disclosed in U.S. Pat. No. 5,827,281 in the name of Levin entitled “Insulated Surgical Scissors,” is to entirely cover the pair of opposing cutting blades with an electrically and thermally insulative material except along corresponding segments of the confronting surfaces. Thus, this '281 patent does not recognize any benefit to providing electrically active surfaces on the pair of opposing cutting blades other than certain segments of the confronting surfaces and aims to prevent such. However, the need for this insulative material also increases the complexity of the scissors.
However, the teachings of the U.S. Pat. No. 5,827,281 patent are somewhat in contrast to the U.S. Pat. No. 5,658,281 patent. The U.S. Pat. No. 5,658,281 patent discloses that it would be desirable to allow surgeons to use the exterior surfaces of the scissors to coagulate tissue. However, the U.S. Pat. No. 5,658,281 patent does not address how to reduce the burning of surrounding tissue addressed by the U.S. Pat. No. 5,827,281 patent, nor any other concerns of tissue desiccation, tissue sticking to the electrodes, coagulum build-up on the electrodes, tissue perforation, char formation and smoke generation which may occur with use of dry electrosurgical devices.
In light of the above, it is an object of the invention to provide devices, systems and methods which overcome the limitations of the art.